The present Application relates to an alarm system for gaining the attention of an individual without use of sound or light. It particularly relates to a system for gaining the attention of an individual who for medical or other reasons is unable to hear. The present invention further relates to a system wherein the individual whose attention is to be gained need not be able to see.
The present invention is hereinafter described with reference to a door bell for use by the deaf and the deaf/blind. It is to be appreciated that the present invention is not restricted to such use. The present invention is equally applicable to situations where sound or light are not readily perceptible to the individual whose attention is to be gained. The present invention is applicable therefore to high noise environments where an individual cannot hear an alarm because of noise masking or because of being required to wear sound excluding eardefenders. The present invention is also applicable for use in the vacuum of space or in underwater situations where sound or light may not readily be transmitted to the ears of the individual whose attention is to be gained.
In attempting to provide a door bell or other selectably operable attention gaining system for a deaf person a difficulty arises in the use of a light alarm in that the person whose attention is to be gained may not at that instant be regarding the controlled light source. There is therefore a high risk of a delay or total omission in perception of the activation of the controlled light source. No light activated system can be guaranteed as effective as an acoustic system in daylight conditions and in artificial light conditions it becomes necessary to control such an unwieldy proportion of the lighting in order to be sure of gaining attention that the system becomes large and cumbersome.
In other situations alarm lights may not immediately be noticed and any associated acoustic device may be masked by excessive sound. Such a situation may occur in the cockpit of an aircraft.
Devices have been proposed which utilize an acoustic buzzer which may also provide some tactile input to a user. The low amplitude and high frequency of such tactile input renders the device ineffective to a deaf person or person not in a position to hear properly if more than a very small amount of clothing is interposed between the acoustic device and the skin of the individual whose attention is to be gained.